Abstract
	The paper deals with the problem of angular vibration measurements in terms of rotation angle, angular velocity or angular acceleration. The source of information about angular vibrations is an incremental rotary encoder producing a string of impulses or another impulse generator. It is supposed that the impulse frequency is changed proportionally to the rotational frequency. A time record of an impulse signal is transformed to an analytical signal using Hilbert transform. The unwrapped phase of the analytical signal gives the rotation angle, which is employed to evaluation of angular velocity and angular acceleration. Signals that are disturbed by noise are enhanced by filtration in the frequency domain. The measurement method described below can be used for inspection of the driving systems for sheet rolling mills in metallurgy industry. Angular vibration measurements can contribute to improve the sheet surface quality. Employing of this new data processing tool is demonstrated on gear transmission error and car engine crankshaft angular vibration measurements.